This invention relates generally to the field of agricultural machinery, especially balers, and more particularly to improvements in regulating the bale length.
A square baler generally includes a pick-up device, a feeding channel, a baling chamber having side-limiting walls, a baling ram, and a device for tying formed bales. A square baler may also have a device to determine the length of the formed crop bundle. One such device comprises a measuring-wheel and an electronic sensor connected to it.
Such a device is disclosed in German Patent 38 09 132. There is a device described which counts the number of strokes of the baling ram as a measurable variable, temporarily stores the number of strokes, and triggers the tying process to tie the harvested crop bale once the pre-set number of strokes is reached. Hence, the number of strokes is used as a measurement or target for the bale length. This arrangement, however, is inconsistent because the amount of crops (i.e. volume) added with an operating stroke does not in all circumstances equal the path of the baling ram. For example, the loading portion could be a small amount when loading starts, or the bale could expand in the direction of the baling ram when it is moving backwards to allow feeding of the next loading portion. Inconsistent or inaccurate bale lengths can be very disruptive because a bale that is too long may not fit on the transport trailer, and a bale that is too short will only partly utilize the transport volume of the trailer.
The device disclosed in German Patent 34 36 883 shows that it is disadvantageous for the measuring wheel to drive a shift-rod via cams. Because of its drive function, the measuring wheel runs relatively sluggishly and stops when the crop bundle felt by the measuring wheel is incompletely filled in the upper area, and therefore does not transfer sufficient power to turn the counting wheel. In addition, due to the attached gearbox, the measuring wheel cannot be mounted resiliently such as by springs.
To overcome the above disadvantage, the connection of an electronic sensor to the measuring wheel is proposed in European Patent 0 573 342. The installation of teeth in the baling channel which prevent backward movement of the crops is proposed therein, to reconcile inaccuracies which are a result of the forward and backward movement of the bale in the baling channel. This reduces the crop feeding capabilities. Also the crop which is not in the operating area of the teeth, especially the crop in the area around the measuring wheel, nevertheless tends to re-expand so that the measuring device supplies inaccurate or unsatisfactory measuring results.
Finally, German Patent 295 11 023 proposes to count only the movements in feeding direction to attain improved accuracy. However, since the bale re-expands, the measured length is smaller than the actual length.
The present invention is directed to overcoming one or more of the above described deficiencies.
It is an object of the present invention to provide a device and a procedure to regulate, more specifically to measure, the bale length so that the pre-set bale length is most accurately ensured.
In accordance with the present invention there is provided a square baler for bailing harvested crops and having a pick-up device, a feeding channel, a baling chamber, a baling ram for forming a crop bundle in the bailing chamber, a tying apparatus for tying the crop bundle and forming a bale, sensing means for sensing both the forward and backward movement of the crop bundle in the bailing chamber; and means responsive to the sensing means for determining the length of the crop bundle and triggering the tying apparatus when a pre-set length for the crop bundle is reached.
The objects are met by introducing an electronic measuring device which measures the forward and backward movement of a crop bundle via the rotational movement of a measuring wheel, then transfers the results to the evaluation electronic, which adds together the measured movements of the crop bundle to an actual-length value and triggers the tying device when the target length-value is approached. On the one hand, the measuring wheel with the attached electronic measuring device can easily be rotated and therefore follows every movement of the crop bundle. On the other hand, by adding-up every forward and backward movement, it is assured that possible errors are precluded by extracting one movement direction, or through the determination of the bale length, on the basis of assumptions of the length measurement.
Also in accordance with the invention there is provided a bailing method for controlling the length of a square bale, comprising the steps of:
sensing both the forward and backward movement of a crop bundle in a baling chamber; adding the measured forward and backward movements of the crop bundle to determine an actual length of the crop bundle; and triggering a tying device once a pre-set target actual length value is reached to tie the crop bundle into a bale.